Carbon dioxide absorption in sodium hydroxide solution was performed in a microstructured falling film gas-liquid reactor. The liquid phase was distributed on a reaction plate of 64 microchannels of 300 × 100 µm having a length of 66.4 mm, while the gas-phase was guided in a gas chamber with a depth of 5.5 mm or 2.5 mm. Experimental data were obtained keeping a fixed overall liquid flowrate of 50 mL/h, using three different NaOH inlet concentration (0.1, 1, and 2 M) and a fixed inlet molar ratio CO 2 :NaOH of 0.4, for a range of CO 2 concentration of 0.8-100%. A plate with 16 microchannels of 1200 µm × 400 µm was also employed. A twodimensional model was formulated to simulate the reactor, and experimental results were compared to model prediction in terms of carbon dioxide conversion. The model gives good agreement with the experimental data at low inlet NaOH concentration (0.1 and 1 M), while the agreement with the experiments at 2 M NaOH is reasonable only for low CO 2 inlet concentration. The model indicates that carbon dioxide is consumed within a short distance from the gas-liquid interface.
A comprehensive review of factors that inhibit scalability of fine chemicals and pharmaceuticals, from the chemical engineering point of view, is presented. These potential scale-up obstacles are generated by the fact that chemical rate constants are scale-independent, whereas physical parameters and phenomena are not. The paper identifies the most common factors that interact with chemistry to cause a fall in performance on scale-up and suggests ways in which these issues can be analysed in order to generate appropriate solutions. A hierarchy of the importance of the potential scale-up obstacles as perceived in industry is presented based on information collected from chemical companies, while the merits of scale-out as opposed to scale-up are addressed.
in Wiley Online Library (wileyonlinelibrary.com).Microscale autothermal reactors remain one of the most promising technologies for efficient hydrogen generation. The typical reactor design alternates microchannels where reforming and catalytic combustion of methane occur, so that exothermic and endothermic reactions take place in close proximity. The influence of flow arrangement on the autothermal coupling of methane steam reforming and methane catalytic combustion in catalytic plate reactors is investigated. The reactor thermal behavior and performance for cocurrent and countercurrent are simulated and compared. A partial overlapping of the catalyst zones in adjacent exothermic and endothermic channels is shown to avoid both severe temperature excursions and reactor extinction. Using an innovative, optimization-based approach for determining the catalyst zone overlap, a solution is provided to the problem of determining the maximum reactor conversion within specified temperature bounds, designed to preserve reactor integrity and operational safety.
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